1. Field of the Invention
This invention relates to rapid transfer port (RTP) systems and more particularly to the decontamination of transfer containers for use with such rapid transfer port (RTP) systems. The RTP systems are of a type for transferring articles between two environments (such as an isolator barrier system and a transfer container) that are adapted to be brought into close proximity to one another by a docking operation.
2. Description of the Related Art
Certain manufacturing processes require the maintenance of separation between two environments to avoid contamination of the cleaner of the two environments by the dirtier of the two. This is accomplished with the use of environments such as isolation barriers. For example, in the case of certain pharmaceutical products, the manufacturing process is performed within these isolation barriers to prevent contamination of the product being produced by dust particles, bacteria and viruses which are found in the outside ambient air. The same holds true for the assembly of certain medical devices. In the case of radioactive operations or bacteriological procedures, the environment within the isolation barrier is dirty as compared to the outside ambient air. In these cases, the isolation barrier serves the function of keeping the product being handled from escaping into the external environment.
In recent years, in the pharmaceutical industry, because of the expense and operational difficulties of maintaining so-called “clean rooms” into which operators enter to carry out procedures, the use of isolation barriers has become common practice. The isolation barriers, in concept large glove boxes, are integrated onto the machinery used to carry out the necessary manufacturing operations. A variation of these isolation barriers is what is commonly known as a RABS, Restricted Access Barrier System.
Means for transferring components, product, supplies, etc. into and out of these isolation barriers without risk of contamination of the components being transferred by the “dirty” external environment during the docking and components transfer process must be provided. To accomplish this, isolator barrier systems and RABS feature devices generally called Rapid Transfer Ports (RTP). These RTP devices may be of various type, size and configuration. A common type of RTP device is one that is offered by the French company La Calhene, referred to as the DPTE. This device requires rotation of the transfer container during the docking process. This type of RTP device is generally mounted on an outer surface of the isolation barrier and features docking attachments for a pre-sterilized transfer container housing the components to be transferred. Upon the docking process, the operator places the transfer container into alignment with the RTP and rotates the container approximately 60 degrees to complete the docking operation. The docking process firmly attaches the transfer container to the RTP and, simultaneously, the transfer container door to the RTP door. Once docked, the operator reaches inside the isolation barrier via gloves located on the isolation barrier wall and opens the RTP door, with it attached the transfer container door, and gains access to the components located within the transfer container. To prevent contamination of the “clean” environment, the docking process places the “dirty” surfaces of the RTP and of the transfer container in sealed contact with each thus not permitting “dirty” particles to escape into the “clean” environment.
The container must be sterilized prior to docking to a sterile isolator barrier. The sterilization process can be a lengthy operation and can therefore be considered a obstacle in meeting the manufacturing flow requirements of the operation. Presently, the sterilization process of the container is accomplished by following one of two basic methods: sterilization using steam or vapor hydrogen peroxide (VHP) bactericide vapor.
VHP gas is produced by an appropriate VHP generator which transform the hydrogen peroxide from its fluid form to the vapor form necessary to cover all surfaces to be sterilized and creates a continuous flow of the gas though the device to be sterilized by means of flow components and proper injection connections.
With either one of the methods of container sterilization, the access door of the RTP container is removed from its receptacle in the container's forward flange to make sure of total coverage by the sterilant (either the steam or the bactericide vapor) of the critical surfaces between the door and the container flange.
Sterilization using steam is normally done inside a steam autoclave. The container is placed on a cart inside an autoclave, the door is removed from the container and a steam sterilization cycle is conducted. At the conclusion of the sterilization cycle, the container is transferred to an isolator which is connected to the exit door of the steam autoclave. An operator, through gloves, can then install the door onto the container thus creating a sterile closed volume within the container. From this point on the canister is ready for use. This sequence requires quite a number of time consuming process steps and it must take place in an autoclave which is normally used to sterilize all parts, availability of this critical piece of equipment is an operational issue in particular for those operations which require continuous flow of sterile canisters.
An alternate method of sterilizing a container using steam is that disclosed in Glachet et al U.S. Pat. No. 5,732,843. The device clamps onto the access door end of the canister to be sterilized and permits removal of the access door to allow coverage of all surfaces by the steam. The steam is introduced into the container by ports located in the container itself. Although capable of steam sterilizing the container, the device requires the container to feature steam injection ports, it is limited in use to a specific type of containers and requires the relative lengthy steam sterilization process to take place. It is seen that, for those applications where quick turn around of the container sterilization cycle is critical to the operation, the system has limitations.
The second method of sterilizing the container prior to use is to expose the surfaces to be sterilized to a bactericide vapor, normally vapor hydrogen peroxide (VHP). This process is normally referred to as a process of decontamination. VHP decontamination of containers is normally done by connecting the container to an RTP port of the isolator barrier where the sterile work takes place, by opening the door of the container while its is attached to the door of the RTP port to which the container is docked and by injecting the whole chamber (isolator barrier and container) with the bactericide vapor. This process of decontamination is quite lengthy and is limited to the one container that is docked to the isolator barrier during the decontamination process. This approach does not work well for those applications which require continuous flow of containers to support the manufacturing process.
A second method of decontaminating the container with vapor hydrogen peroxide is to make use of the same device previously discussed that is disclosed in Glachet et al U.S. Pat. No. 5,732,843. The device and its use have some restrictions which one might consider to be operationally undesirable; specifically, the device requires the presence of inlet and outlet openings in the container itself, thus placing limitations on the configuration of the container itself. In addition, the device does not include means for proper distribution of the bactericide vapor over all surfaces of the door end of the container and the system creates a volume that is of such small magnitude that existing VHP generator technology could experience difficulties in maintaining proper positive pressure during the decontamination cycle.